Features for non-web game engines

src/core/body.js

@@ -363,6 +363,17 @@
             scratch.done();
         },
 
+        /**
+         * Body#onStep() -> this
+         *
+         * Intended to be overridden by subclasses. Called when the associated
+         * world is stepped.
+         **/
+        onStep: function() {
+            // Override this function to update any associated graphic
+            return this;
+        },
+
         /**
          * Body#setWorld( world ) -> this
          * - world (Object): The world (or null)
@@ -372,15 +383,21 @@
          * Usually this is called internally. Shouldn't be a need to call this yourself usually.
          **/
         setWorld: function( world ){
-
-            if ( this.disconnect && this._world ){
-                this.disconnect( this._world );
+            if(this._world) {
+                this._world.off("step", this.onStep);
+                if ( this.disconnect ){
+                    this.disconnect( this._world );
+                }
             }
 
             this._world = world;
 
-            if ( this.connect && world ){
-                this.connect( world );
+            if(this._world) {
+                this._world.on("step", this.onStep, this);
+
+                if ( this.connect ){
+                    this.connect( this._world );
+                }
             }
 
             return this;

src/core/world.js

@@ -641,6 +641,27 @@
             this._integrator.integrate( this._bodies, dt );
         },
 
+        /** chainable
+         * Physics.world#stepDelta( dt ) -> this
+         * - dt (Number): Delta time in ms
+         * 
+         * Step the world BY a specified change in time
+         */
+        stepDelta: function(dt) {
+            // If paused or at the first step, calculate the appropriate time
+            if ( this._paused || this._animTime === undefined ){
+                this._animTime = this._animTime || Physics.util.ticker.now();
+            }
+
+            // Do nothing while paused
+            if(this._paused) {
+                return this;
+            }
+
+            // Otherwise increment the current animation time and step normally
+            return this.step(this._animTime.valueOf() + dt);
+        },
+
         /** chainable
          * Physics.world#step( [now] ) -> this
          * - now (Number): Current unix timestamp

src/util/helpers.js

@@ -38,6 +38,22 @@ Physics.util.clearArray = function clearArray(arr){
     return arr;
 };
 
+/**
+ * Physics.util.rad2deg(radians) -> Number
+ * radians (Number): Radians to convert to degrees
+ */
+Physics.util.rad2deg = function rad2deg(radians) {
+  return radians * (180/3.14159265);
+};
+
+/**
+ * Physics.util.deg2rad(radians) -> Number
+ * degrees (Number): Degrees to convert to radians
+ */
+Physics.util.deg2rad = function deg2rad(degrees) {
+  return degrees * (3.14159265/180);
+};
+
 /**
  * Physics.util.throttle( fn, delay ) -> Function
  * - fn (Function): The function to throttle